Methods and systems for forming metal-containing films on substrates

ABSTRACT

A method of forming a film on a substrate using Group IVB, VB, or VIB metal complexes. The methods are particularly suitable for the preparation of semiconductor structures using chemical vapor deposition techniques and systems.

FIELD OF THE INVENTION

This invention relates to methods and complexes for formingmetal-containing films, such as metal or metal alloy films, onsubstrates, particularly during the manufacture of semiconductor devicestructures. The complexes include a Group IVB, VB, or VIB metal and areparticularly suitable for use in a chemical vapor deposition system.

BACKGROUND OF THE INVENTION

As device geometries shrink it is becoming increasingly important tolook at alternatives for titanium as a contact/barrier material. Forexample, as contact holes or vias (i.e., very small openings located,for example, between surface conductive paths and or “wiring” and activedevices on underlying layers) become narrower and deeper, they areharder to fill with metal. Also, metalorganic sources for titaniumnitride, for example, which is used as a metallization barrier, areparticularly difficult to find that have sufficiently low and stableresistance to be suitable for very small contacts. Furthermore, it isdifficult to deposit pure titanium by chemical vapor deposition at lowtemperatures because currently available precursors require hightemperatures to remove halogen from films deposited from titaniumhalides or are contaminated with carbon when common metalorganicprecursors are used.

Thus, there is a continuing need for methods and precursor compositionsfor the deposition of titanium and metals that are suitable replacementsfor titanium in metal-containing films, on substrates such as those usedin semiconductor structures, particularly using vapor depositionprocesses.

SUMMARY OF THE INVENTION

The present invention provides methods for forming metal-containingfilms, particularly Group IVB, VB, and VIB metal-containing films onsubstrates, such as semiconductor substrates or substrate assembliesduring the manufacture of semiconductor structures. Group IVB (i.e.,Group 4) includes Ti, Zr, and Hf. Group VB (i.e., Group 5) includes V,Nb, and Ta. Group VIB (i.e., Group 6) includes Cr, Mo, and W. Themethods involve forming a metal-containing film using a Group IVB, VB,or VIB metal complex, preferably a Group VB metal complex. Themetal-containing film can be used in various metallization layers,particularly in multilevel interconnects, in integrated circuitstructures.

The metal-containing film can be a single Group IVB, VB, or VIB metal,or a metal alloy containing a mixture of such metals or one or moremetals from these groups and one or more metals or metalloids from othergroups in the Periodic Chart, such as Si, Ge, Sn, Pb, Bi, etc.Furthermore, for certain preferred embodiments, the metal-containingfilm can be a nitride, phosphide, arsenide, stibnide, sulfide, selenide,telluride, or combinations thereof.

Thus, in the context of the present invention, the term “Group IVB-VIBmetal-containing film” or simply “metal-containing film” includes, forexample, relatively pure films of titanium, zirconium, hafnium,vanadium, niobium, tantalum, chromium, molybdenum, or tungsten. The termalso includes alloys of such metals with or without other metals ormetalloids, as well as complexes of these metals and alloys with otherelements (e.g., N, P, As, Sb, S, Se, and Te), or mixtures thereof. Theterms “single Group IVB-VIB metal film” or “Group IVB-VIB metal film”refer to relatively pure films of titanium, zirconium, hafnium,vanadium, niobium, tantalum, chromium, molybdenum, or tungsten. The term“metal alloy film” refers to films containing titanium, zirconium,hafnium, vanadium, niobium, tantalum, chromium, molybdenum, and tungstenin various combinations with each other or with other metals ormetalloids. That is, if there are no metals or metalloids from groups inthe Periodic Chart other than those from Groups IVB, VB, or VIB, thealloy films contain combinations of titanium, zirconium, hafnium,vanadium, niobium, tantalum, chromium, molybdenum, and tungsten.

One preferred method of the present invention involves forming a film ona substrate, such as a semiconductor substrate or substrate assemblyduring the manufacture of a semiconductor structure, by providing asubstrate (preferably, a semiconductor substrate or substrate assembly),and providing a precursor composition comprising one or more complexesof the formula:

[(R¹)NC(R²)C(R³)N(R⁴)]_(x)ML_(y)  (Formula I)

wherein: M is a Group IVB, VB, or VIB metal; each R¹, R², R³, and R⁴group is independently H or an organic group; L is selected from thegroup of CO, NO, CN, CS, CNR⁵, R⁶CN, or R⁷, wherein each R⁵, R⁶, and R⁷group is independently an organic group; x=1 to 4; and y=1 to 4; andforming a metal-containing film from the precursor composition on asurface of the substrate (preferably, a semiconductor substrate orsubstrate assembly). Using such methods the complexes of Formula I areconverted in some manner (e.g., thermally decomposed) and deposited on asurface to form a metal-containing film. Thus, the film is not a film ofthe complex of Formula I, but may contain only the Group IVB, VB, or VIBmetal, M, or metal alloys, for example.

As used herein, Formula I is an empirical formula. That is, it expressesin simplest form the relative number of atoms in a molecule. Thus, thecompounds of Formula I can be monomers, dimers, trimers, etc. Typically,however, they are monomers and Formula I is the actual molecularformula. Such complexes are typically referred to as “diazadiene” or“diazabutadiene” complexes.

Complexes of Formula I are neutral complexes and may be liquids orsolids at room temperature. If they are solids, they are preferablysufficiently soluble in an organic solvent or have melting points belowtheir decomposition temperatures such that they can be used in flashvaporization, bubbling, microdroplet formation techniques, etc. However,they may also be sufficiently volatile that they can be vaporized orsublimed from the solid state using known chemical vapor depositiontechniques. Thus, the precursor compositions of the present inventioncan be in solid or liquid form. As used herein, “liquid” refers to asolution or a neat liquid (a liquid at room temperature or a solid atroom temperature that melts at an elevated temperature). As used herein,a “solution” does not require complete solubility of the solid; rather,the solution may have some undissolved material, preferably, however,there is a sufficient amount of the material that can be carried by theorganic solvent into the vapor phase for chemical vapor depositionprocessing. Thus, a vaporized precursor composition includes vaporizedmolecules of precursor complexes of Formula I either alone or optionallywith vaporized molecules of other compounds in the precursorcomposition, including solvent molecules, if used.

Preferred embodiments of the methods of the present invention involvethe use of one or more chemical vapor deposition techniques, althoughthis is not necessarily required. That is, for certain embodiments,sputtering, spin-on coating, etc., can be used.

Methods of the present invention are particularly well suited forforming films on a surface of a semiconductor substrate or substrateassembly, such as a silicon wafer, with or without layers or structuresformed thereon, used in forming integrated circuits. It is to beunderstood that methods of the present invention are not limited todeposition on silicon wafers; rather, other types of wafers (e.g.,gallium arsenide wafer, etc.) can be used as well. Also, methods of thepresent invention can be used in silicon-on-insulator technology.Furthermore, substrates other than semiconductor substrates or substrateassemblies, can be used in methods of the present invention. Theseinclude, for example, fibers, wires, etc. If the substrate is asemiconductor substrate or substrate assembly, the films can be formeddirectly on the lowest semiconductor surface of the substrate, or theycan be formed on any of a variety of the layers (i.e., surfaces) as in apatterned wafer, for example. Thus, the term “semiconductor substrate”refers to the base semiconductor layer, e.g., the lowest layer ofsilicon material in a wafer or a silicon layer deposited on anothermaterial such as silicon-on-sapphire. The term “semiconductor substrateassembly” refers to the semiconductor substrate having one or morelayers or structures formed thereon.

A chemical vapor deposition system is also provided. The system includesa deposition chamber having a substrate positioned therein; a vesselcontaining a precursor composition comprising one or more complexes ofFormula I; and a source of an inert carrier gas for transferring theprecursor composition to the chemical vapor deposition chamber.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a cross-sectional schematic of a semiconductor contact or viahaving a film deposited in accordance with the method of the presentinvention.

FIG. 2 is a schematic of a chemical vapor deposition system suitable foruse in the method of the present invention.

FIG. 3 is a schematic of an alternative chemical vapor deposition systemsuitable for use in the method of the present invention.

DETAILED DESCRIPTION

The present invention provides a method of forming a metal-containingfilm using one or more complexes of Formula (I):

[(R¹)NC(R²)C(R³)N(R⁴)]_(x)ML_(y)  (I)

wherein M is a Group IVB, VB, or VIB metal; each R¹, R², R³, and R⁴group is independently H or an organic group (preferably, a(C₁-C₃₀)organic group); L is selected from the group of CO, NO, CN, CS,CNR⁵, R⁶CN, or R⁷, wherein each R⁵, R⁶, and R⁷ group is independently anorganic group (preferably, a (C₁-C₃₀)organic group, more preferably, R⁷is cyclopentadienyl); x=1 to 4 (preferably, 2 or 3); and y=1 to 4. In apreferred embodiment, complexes of Formula I include a Group VB metal.Preferably, such complexes are mononuclear (i.e., monomers in that theycontain one metal per molecule). Thus, the complexes are preferablymononuclear diazadiene (i.e., diazabutadiene) complexes. Preferredembodiments display few intermolecular forces of attraction. However, itis also possible for one or more molecules of Formula I to combine toform dimers, trimers, etc. Thus, the complexes of Formula I areexpressed in their simplest form, i.e., Formula I is an empiricalformula.

The complexes of Formula I are neutral complexes and may be liquids orsolids at room temperature. If they are solids, they are sufficientlysoluble in an organic solvent to allow for flash vaporization, or theycan be vaporized or sublimed from the solid state, or they have meltingtemperatures below their decomposition temperatures. Thus, many of thecomplexes described herein are suitable for use in chemical vapordeposition (CVD) techniques, such as flash vaporization techniques,bubbler techniques, and/or microdroplet techniques. Depositions can alsobe carried out with assistance of plasma or photolysis. Preferredembodiments of the complexes described herein are particularly suitablefor low temperature CVD, e.g., deposition techniques involving substratetemperatures of about 100° C. to about 400° C.

The solvents that are suitable for this application can be one or moreof the following: saturated or unsaturated branched, linear, or cyclicaliphatic (alicyclic) hydrocarbons (C₃-C₂₀, and preferably C₅-C₁₀),aromatic hydrocarbons (C₅-C₂₀, and preferably C₅-C₁₀), halogenatedhydrocarbons, silylated hydrocarbons such as alkylsilanes,alkylsilicates, ethers, polyethers, thioethers, esters, lactones,ammonia, amides, amines (aliphatic or aromatic, primary, secondary, ortertiary), polyamines, nitrites, cyanates, isocyanates, thiocyanates,silicone oils, aldehydes, ketones, diketones, carboxylic acids, water,alcohols, thiols, or compounds containing combinations of any of theabove or mixtures of one or more of ihe above. It should be noted thatsome precursor complexes are sensitive to reactions with proticsolvents, and examples of these noted above may not be ideal, dependingon the nature of the precursor complex. The complexes are also generallycompatible with each other, so that mixtures of variable quantities ofthe complexes will not interact to significantly change their physicalproperties.

One preferred method of the present invention involves vaporizing aprecursor composition that includes one or more Group IVB, VB, or VIBmetal complexes of Formula I. For certain embodiments, the precursorcomposition can also include one or more complexes containing metals ormetalloids other than Group IVB, VB, or VIB metals. For example, theprecursor composition can include a compound containing N, P, As, or Sb.

The precursor composition can be vaporized in the presence of an inertcarrier gas to form a relatively pure metal or metal alloy film. Theinert carrier gas is typically selected from the group consisting ofnitrogen, helium, and argon. In the context of the present invention, aninert carrier gas is one that is generally unreactive with the complexesdescribed herein and does not interfere with the formation of themetal-containing film.

Alternatively, the precursor composition can be vaporized in thepresence of a reaction gas to form a film. The reaction gas can beselected from a wide variety of gases reactive with the complexesdescribed herein, at least at a surface under the conditions of chemicalvapor deposition. Examples of reaction gases include H₂, SiH₄, Si₂H₆,NH₃, N₂H₄, PH₃, AsH₃, GeH₄, t-BuSbMe₂,H₂S, H₂Se, and Te(allyl)₂. Variouscombinations of carrier gases and/or reaction gases can be used in themethods of the present invention to form metal-containing films. Thus,the metal-containing film can include a nitride, phosphide, arsenide,stibnide, sulfide, selenide, telluride, or combinations thereof. Suchmetal-containing films can also be formed by subjecting a relativelypure metal film to subsequent processing, such as annealing or rapidthermal oxidation, to form other metal-containing films, such as oxidesor silicides, for example.

Preferably, the Group IVB, VB, or VIB metal complexes of Formula Idescribed herein are complexes having a coordination number of 3 to 8with at least one diazabutadiene ligand, which is typically bidentate.Complexes such as these are advantageous because no other reactioncompounds (e.g., reductants) are typically required to deposit the metalon a substrate and cleanly volatilize the ligands away without theincorporation of carbon and nitrogen impurities.

The Group IVB, VB, or VIB metal complex is of the following empiricalformula:

[(R¹)NC(R²)C(R³)N(R⁴)]_(x)ML_(y)  (Formula I)

wherein: M is a Group IVB, VB, or VIB metal, and preferably, V, Nb, orTa; each R (i.e., R¹, R², R³, R⁴) is independently H or an organicgroup; L is selected from the group of CO, NO, CN, CS, CNR⁵, R⁶CN, orR⁷, wherein each R⁵, R⁶, and R⁷ group is independently an organic group;x=1 to 4 (preferably, x=2 or 3); y=1 to 4. The ligand[(R¹)NC(R²)C(R³)N(R⁴)] typically bonds to the central metal through thenitrogen atoms as follows:

The ligands L can be organic groups (R⁷) that can be joined to form aring or rings with the metal. Preferably, these organic groups include1-30 carbon atoms, and more preferably, 1-8 carbon atoms. Mostpreferably, L is cyclopentadienyl or substituted cyclopentadienyl. Ofthe metals, vanadium is particularly preferred because it will reactwith native silicon oxide to form a good contact. Vanadium suicides andnitrides are also as good or better conductors than their titaniumanalogs.

As used herein, the term “organic group” means a hydrocarbon group (withoptional elements other than carbon and hydrogen, such as oxygen,nitrogen, sulfur, and silicon) that is classified as an aliphatic group,cyclic group, or combination of aliphatic and cyclic groups (e.g.,alkaryl and aralkyl groups). In the context of the present invention,the organic groups are those that do not interfere with the formation ofa metal-containing film. Preferably, they are of a type and size that donot interfere with the formation of a metal-containing film usingchemical vapor deposition techniques. The term “aliphatic group” means asaturated or unsaturated linear or branched hydrocarbon group. This termis used to encompass alkyl, alkenyl, and alkynyl groups, for example.The term “alkyl group” means a saturated linear or branched hydrocarbongroup including, for example, methyl, ethyl, isopropyl, t-butyl, heptyl,dodecyl, octadecyl, amyl, 2-ethylhexyl, and the like. The term “alkenylgroup” means an unsaturated, linear or branched hydrocarbon group withone or more carbon-carbon double bonds, such as a vinyl group. The term“alkynyl group” means an unsaturated, linear or branched hydrocarbongroup with one or more carbon-carbon triple bonds. The term “cyclicgroup” means a closed ring hydrocarbon group that is classified as analicyclic group, aromatic group, or heterocyclic group. The term“alicyclic group” means a cyclic hydrocarbon group having propertiesresembling those of aliphatic groups. The term “aromatic group” or “arylgroup” means a mono- or polynuclear aromatic hydrocarbon group. The term“heterocyclic group” means a closed ring hydrocarbon in which one ormore of the atoms in the ring is an element other than carbon (e.g.,nitrogen, oxygen, sulfur, etc.).

Substitution is anticipated in the complexes of the present invention.As a means of simplifying the discussion and the recitation of certainterminology used throughout this application, the terms “group” and“moiety” are used to differentiate between chemical species that allowfor substitution or that may be substituted and those that do not soallow or may not be so substituted. Thus, when the term “group” is usedto describe a chemical substituent, the described chemical materialincludes the unsubstituted group and that group with nonperoxidic O, N,or S atoms, for example, in the chain (as in an alkoxy group) as well ascarbonyl groups or other conventional substitution. Where the term“moiety” is used to describe a chemical compound or substituent, only anunsubstituted chemical material is intended to be included. For example,the phrase “alkyl group” is intended to include not only pure open chainsaturated hydrocarbon alkyl substituents, such as methyl, ethyl, propyl,t-butyl, and the like, but also alkyl substituents bearing furthersubstituents known in the art, such as hydroxy, alkoxy, alkylsulfonyl,halogen atoms, cyano, nitro, amino, carboxyl, etc. Thus, “alkyl group”includes ether groups, haloalkyls, nitroalkyls, carboxyalkyls,hydroxyalkyls, sulfoalkyls, etc. On the other hand, the phrase “alkylmoiety” is limited to the inclusion of only pure open chain saturatedhydrocarbon alkyl substituents, such as methyl, ethyl, propyl, t-butyl,and the like.

The R groups can be joined to form a ring or rings, which may or may nothave unsaturation, including aromaticity. Preferred R groups (R¹, R²,R³, and R⁴) in the complexes of Formula I, include H or (C₁-C₃₀)organicgroups. More preferred R groups (R¹, R², R³, and R⁴) are H or(C₁-C₂₀)organic groups. Most preferred R groups (R¹, R², R³, and R⁴) areH or (C₁-C₈)organic groups. For certain embodiments, (C₁-C₆)organicgroups are particularly preferred. Of the organic groups, nonaromaticgroups (e.g., aliphatic groups and alicyclic groups, which may or maynot include unsaturation, and which may or may not include heteroatomssuch as N, O, S, P, Si, etc.) are preferred. Of these, the aliphaticgroups are more preferred, and alkyl moieties (particularly “lower”(C₁-C₄)alkyl moieties) are most preferred. Thus, for particularlypreferred complexes of Formula I, each R group (R¹, R², R³, and R⁴) canbe H or a (C₁-C₄)alkyl moiety.

Various combinations of the complexes described herein can be used in aprecursor composition. Thus, as used herein, a “precursor composition”refers to a liquid or solid that includes one or more complexes of theformulas described herein optionally mixed with one or more complexes offormulas other than those of Formula I. The precursor composition canalso include one or more organic solvents suitable for use in a chemicalvapor deposition system, as well as other additives, such as freeligands, that assist in the vaporization of the desired compounds.

The complexes described herein can be used in precursor compositions forchemical vapor deposition. Alternatively, certain complexes describedherein can be used in other deposition techniques, such as sputtering,spin-on coating, and the like. Typically, those complexes containing Rgroups with a low number of carbon atoms (e.g., 1-4 carbon atoms per Rgroup) are suitable for use with CVD techniques. Those complexescontaining R groups with a higher number of carbon atoms (e.g., 5-12carbon atoms per R group) are generally suitable for spin-on or dipcoating. Preferably, however, chemical vapor deposition techniques aredesired because they are more suitable for deposition on semiconductorsubstrates or substrate assemblies, particularly in contact openingswhich are extremely small and require conformally filled layers ofmetal.

For the preparation of alloy films, two or more complexes of Formula Ican be combined in a precursor composition mixture (e.g.,V(CO)_(y)(^(t)BuN═CHCH═N^(t)Bu) and Nb(CO)_(y)(^(t)BuN═CHCH═N^(t)Bu) fora V/Nb alloy). Alternatively, at least one complex of Formula I can becombined with another complex in a precursor composition mixture (e.g.,Ti(C₅H₅)(^(i)PrN═CHCH═N^(i)Pr)₂ and Al(Et)₃ for a Ti/Al alloy).

The complexes of the present invention can be prepared by a variety ofmethods known to one of skill in the art. For example,V(CO)_(y)(^(t)BuN═CHCH═N^(t)Bu) can be prepared by reduction of VCl₃with Na in the presence of (^(t)BuN═CHCH═N^(t)Bu) and CO.

As stated above, the complexes of Formula I and methods of formingmetal-containing films of the present invention are beneficial for awide variety of thin film applications in semiconductor structures,particularly various metallization layers. Such applications includemultilevel interconnects in an integrated circuit structure. A film canbe deposited in a wide variety of thicknesses, depending on the desireduse. Typically, thin films of Group IVB, VB, or VIB metals, such asvanadium, and alloys thereof are deposited as polycrystalline materials,usually in a range of about 0.5μm to about 1.5μm thick.

A specific example of where a film formed from the complexes of thepresent invention would be useful is the structure shown in FIG. 1. Thestructure may be in the form of an n-channel MOSFET (n-channelmetal-oxide semiconductor field-effect transistor), which may be used ina DRAM (dynamic random access memory) device. As shown, substrate 16 isa p-type silicon having two n-type silicon islands 20 and 22,representing the transistor source and drain. Such a construction iswell known. The gate for the transistor is formed by a metal/polysiliconlayer 24 deposited over a silicon dioxide layer 26. A relatively thicklayer of an insulating silicon dioxide 28 overlies the active areas onsubstrate 16.

To connect the MOSFET with electrically conductive paths (i.e., metallines) on the surface of the device, contacts 30 and 32 have been etchedthrough oxide layer 28 down to the surface of substrate 16. A metal ormetal silicide layer 34, such as vanadium silicide or othermetal-containing film prepared by the methods of the present invention,is deposited and formed at the base of contact holes 30 and 32. A thin,conformal barrier layer 36 of a conductive material, such as titaniumnitride, titanium aluminum nitride, titanium nitride silicide, tantalumnitride, or other metal-containing film prepared by the methods of thepresent invention, is deposited over the walls of the contact holes 30and 32. Because of the presence of the conductive barrier layer 36, theelectrical contact path is excellent and the metal 38 (e.g., Al or Cu)which is deposited over barrier layer 36 is prevented from attacking thesubstrate surfaces.

Methods of the present invention can be used to deposit ametal-containing film, preferably a metal or metal alloy film, on avariety of substrates, such as a semiconductor wafer (e.g., siliconwafer, gallium arsenide wafer, etc.), glass plate, etc., and on avariety of surfaces of the substrates, whether it be directly on thesubstrate itself or on a layer of material deposited on the substrate asin a semiconductor substrate assembly. The film is deposited upondecomposition (typically, thermal decomposition) of a complex of FormulaI, preferably one that is either a volatile liquid, a sublimable solid,or a solid that is soluble in a suitable solvent that is not detrimentalto the substrate, other layers thereon, etc. Preferably, however,solvents are not used; rather, the transition metal complexes are liquidand used neat. Methods of the present invention preferably utilize vapordeposition techniques, such as flash vaporization, bubbling, etc.

A typical chemical vapor deposition (CVD) system that can be used toperform the process of the present invention is shown in FIG. 2. Thesystem includes an enclosed chemical vapor deposition chamber 10, whichmay be a cold wall-type CVD reactor. As is conventional, the CVD processmay be carried out at pressures of from atmospheric pressure down toabout 10³¹ ³ torr, and preferably from about 10 torr to about 0.1 torr.A vacuum may be created in chamber 10 using turbo pump 12 and backingpump 14.

One or more substrates 16 (e.g., semiconductor substrates or substrateassemblies) are positioned in chamber 10. A constant nominal temperatureis established for the substrate, preferably at a temperature of about100° C. to about 400° C., and more preferably at a temperature of about100° C. to about 300° C. Substrate 16 may be heated, for example, by anelectrical resistance heater 18 on which substrate 16 is mounted. Otherknown methods of heating the substrate may also be utilized.

In this process, the precursor composition 40, which contains one or orecomplexes of Formula I (and/or other metal or metalloid complexes), isstored in liquid form (a neat liquid at room temperature or at anelevated temperature if solid at room temperature) in vessel 42. Asource 44 of a suitable inert gas is pumped into vessel 42 and bubbledthrough the neat liquid (i.e., without solvent) picking up the precursorcomposition and carrying it into chamber 10 through line 45 and gasdistributor 46. Additional inert carrier gas or reaction gas may besupplied from source 48 as needed to provide the desired concentrationof precursor composition and regulate the uniformity of the depositionacross the surface of substrate 16. Valves 50-54 are opened and closedas required.

Generally, the precursor composition is pumped into the CVD chamber 10at a flow rate of about 1 sccm (standard cubic centimeters) to about1000 sccm. Similar flow rates can be used for inert and reaction gases,if used. The semiconductor substrate is exposed to the precursorcomposition at a pressure of about 0.001 torr to about 100 torr for atime of about 0.01 minute to about 100 minutes. In chamber 10, theprecursor composition will form an adsorbed layer on the surface of thesubstrate 16. As the deposition rate is temperature dependent,increasing the temperature of the substrate will increase the rate ofdeposition in a certain temperature range. Typical deposition rates areabout 10 Angstroms/minute to about 1000 Angstroms/minute. The carriergas containing the precursor composition is terminated by closing valve53.

An alternative CVD system that can be used to perform the process of thepresent invention is shown in FIG. 3. The system includes an enclosedchemical vapor deposition chamber 110, which may be a cold wall-type CVDreactor, in which a vacuum may be created using turbo pump 112 andbacking pump 114. One or more substrates 116 (e.g., semiconductorsubstrates or substrate assemblies) are positioned in chamber 110.Substrate 116 may be heated as described with reference to FIG. 2 (forexample, by an electrical resistance heater 118).

In this process, one or more solutions 60 of one or more precursorcomplexes of Formula I (and/or other metal or metalloid complexes), arestored in vessels 62. The solutions are transferred to a mixing manifold64 using pumps 66. The resultant precursor composition containing one ormore precursor complexes and one or more organic solvents is thentransferred along line 68 to vaporizer 70, to volatilize the precursorcomposition. A source 74 of a suitable inert gas is pumped intovaporizer 70 for carrying volatilized precursor composition into chamber110 through line 75 and gas distributor 76. Reaction gas may be suppliedfrom source 78 as needed. Valves 80-85 are opened and closed asrequired. Similar pressures and temperatures to those described withreference to FIG. 2 can be used.

Alternatives to such methods include an approach wherein the precursorcomposition is heated and vapors are drawn off and controlled by a vapormass flow controller, and a pulsed liquid injection method as describedin “Metalorganic Chemical Vapor Deposition By Pulsed Liquid InjectionUsing An Ultrasonic Nozzle: Titanium Dioxide on Sapphire from Titanium(IV) Isopropoxide,” by Versteeg, et al., Journal of the American CeramicSociety, 78, 2763-2768 (1995). The complexes of Formula I are alsoparticularly well suited for use with vapor deposition systems, asdescribed in copending application U.S. Ser. No. 08/720,710 entitled“Method and Apparatus for Vaporizing Liquid Precursor compositions andSystem for Using Same,” filed on Oct. 2, 1996. Generally, one methoddescribed therein involves the vaporization of a precursor compositionin liquid form (neat or solution). In a first stage, the precursorcomposition is atomized or nebulized generating high surface areamicrodroplets or mist. In a second stage, the constituents of themicrodroplets or mist are vaporized by intimate mixture of the heatedcarrier gas. This two stage vaporization approach provides areproducible delivery for precursor compositions (either in the form ofa neat liquid or solid dissolved in a liquid medium) and providesreasonable growth rates, particularly in device applications with smalldimensions.

Various combinations of carrier gases and/or reaction gases can be usedin certain methods of the present invention. They can be introduced intothe chemical vapor deposition chamber in a variety of manners, such asdirectly into the vaporization chamber or in combination with theprecursor composition.

Although specific vapor deposition processes are described by referenceto FIGS. 2-3, methods of the present invention are not limited to beingused with the specific vapor deposition systems shown. Various CVDprocess chambers or reaction chambers can be used, including hot wall orcold wall reactors, atmospheric or reduced pressure reactors, as well asplasma enhanced reactors. Furthermore, methods of the present inventionare not limited to any specific vapor deposition techniques.

The following examples are offered to further illustrate the variousspecific and preferred embodiments and techniques. It should beunderstood, however, that many variations and modifications may be madewhile remaining within the scope of the present invention.

EXAMPLES Example 1 Preparation of V(CO)_(y)(^(t)BuN═CHCH═N^(t)Bu)

In an inert-atmosphere glove box, VCl₃ (3.0_(g), 5 0.019 mol) is addedto a flask. The solid is dissolved in 100 mL of tetrahydrofuran (THF).To this solution is added bis (tert-butyl)diazabutadiene (2.93 g, 0.019mol), followed by sodium wire (138 g, 0.060 mol). The mixture is stirredunder an atmosphere of carbon monoxide (which is periodically replacedwith fresh CO) for 24 hours. The solvent is then removed in vacuo andthe product is extracted into hexanes and filtered. The filtrate is thenconcentrated and cooled to near 0° C. to precipitate the product. Theproduct is isolated by removing the mother liquor from the precipitateand drying the precipitate in vacuo.

Example 2 Preparation of (C₅H₅) Ti (^(t)BuN═CHCH═N^(t)Bu)

In an inert-atmosphere glove box, (C₅H₅)TiCl₃ (5.0 g, 0.023 mol) isdissolved in 100 mL of THF. Solid bis(tert-butyl)diazabutadiene (3.50 g,0.023 mol) and sodium wire (1.60 g, 0.07 mol) are added, resultin Themixture is stirred for 18 hours, after which time the solvent is removedin vacuo. The product is redissolved in hexanes and filtered; then thehexanes removed in vacuo, leaving the crude product. The product isfurther purified by subliming onto a cold finger in a vacuum.

Example 3 Preparation of Mo(CO)_(y)(^(t)BuN═CHCH═N^(t)Bu)

A Schlenk flask is charged with 5.0 g (0.019 mol) of Mo(CO)₆ (StremChemicals Inc., Newburyport, Mass.). The Mo(CO)₆ is dissolved in 100 mLof benzene, along with 2.93 g (0.019 mol) ofbis(tert-butyl)diazabutadiene. The flask is equipped with a refluxcondenser and the mixture is refluxed under an argon atmosphere for 18hours. The product is isolated by removal of the solvent. It is furtherpurified by subliming onto a cold finger in a vacuum.

Example 4 Preparation of Thin Films

A patterned semiconductor wafer is loaded into a CVD chamber, and thewafer heated to approximately 350° C. The precursor composition,V(CO)_(y)(^(t)BuN═CHCH═N^(t)Bu), is loaded into a conventional stainlesssteel bubbler inside a glove box, and the bubbler transferred to the CVDsystem. A helium carrier gas flow of 50 standard cubic centimeters perminute (sccm) is established through the bubbler, and a chamber pressureof 0.5 torr is established. A reactant gas flow of 50 sccm hydrogen isintroduced separately. The deposition is carried out until a desiredthickness of vanadium metal is obtained on the wafer.

The foregoing detailed description and examples have been given forclarity of understanding only. No unnecessary limitations are to beunderstood therefrom. The invention is not limited to the exact detailsshown and described, for variations obvious to one skilled in the artwill be included within the invention defined by the claims. Thecomplete disclosures of all patents, patent documents, and publicationslisted herein are incorporated by reference, as if each wereindividually incorporated by reference.

What is claimed is:
 1. A method of manufacturing a semiconductorstructure, the method comprising: providing a semiconductor substrate orsubstrate assembly; providing a precursor composition comprising one ormore complexes of the formula: [(R¹)NC(R²)C(R³)N(R⁴)]_(x)ML_(y) wherein: M is a Group IVB, VB, or VIB metal; each R¹, R², R³, and R⁴group is independently H or an organic group; L is selected from thegroup of CO, NO, CN, CS, CNR⁵, R⁶CN, or R⁷, wherein each R⁵, R⁶, and R⁷group is independently an organic group; x=1 to 4; and y=1 to 4; andforming a metal-containing film from the precursor composition on asurface of the semiconductor substrate or substrate assembly.
 2. Themethod of claim 1 wherein the step of forming a metal-containing filmcomprises vaporizing the precursor composition and directing it towardthe semiconductor substrate or substrate assembly using a chemical vapordeposition technique.
 3. The method of claim 2 wherein the chemicalvapor deposition technique comprises flash vaporization, bubbling,microdroplet formation, or combinations thereof.
 4. The method of claim2 wherein the precursor composition is vaporized in the presence of acarrier gas.
 5. The method of claim 2 wherein the precursor compositionis vaporized in the presence of a reaction gas.
 6. The method of claim 5wherein the reaction gas is selected from the group of H₂, SiH₄, Si₂H₆,NH₃, N₂H₄, PH₃, AsH₃, GeH₄, t-BuSbMe₂, H₂S, H₂Se, Te(allyl)₂, andcombinations thereof.
 7. The method of claim 1 wherein each R¹, R², R³,and R⁴ group is independently H or a (C₁-C₃₀)organic group.
 8. Themethod of claim 1 wherein the complex is a monomer.
 9. The method ofclaim 1 wherein each R¹, R², R³, and R⁴ group is independently H or a(C₁-C₄)alkyl moiety.
 10. The method of claim 1 wherein R⁷ iscyclopentadienyl or a substituted cyclopentadienyl.
 11. The method ofclaim 1 wherein the precursor composition is a liquid.
 12. The method ofclaim 1 wherein the metal is a Group VB metal.
 13. The method of claim12 wherein the metal is vanadium.
 14. The method of claim 1 wherein themetal-containing film is a Group IVB, VB, or VIB metal alloy film.
 15. Amethod of forming a film on a substrate, the method comprising:providing a substrate; providing a precursor composition comprising oneor more complexes of the formula: [(R¹)NC(R²)C(R³)N(R⁴)]_(x)ML_(y) wherein: M is a Group IVB, VB, or VIB metal; each R¹, R², R³, and R⁴ isindependently H or an organic group; L is selected from the group of CO,NO, CN, CS, CNR⁵, R⁶CN, or R⁷, wherein each R⁵, R⁶, and R⁷ group isindependently an organic group x=1 to 4; and y=1 to 4; and forming ametal-containing film from the precursor composition on a surface of thesubstrate.
 16. The method of claim 15 wherein the step of forming ametal-containing film comprises vaporizing the precursor composition anddirecting it toward the substrate using a chemical vapor depositiontechnique.
 17. The method of claim 14 wherein the precursor compositionis liquid.